Photocleavable derivatives of hydroxyprenesulfonic acids

A mixture comprising an aqueous solution of a photoactive compound of the formula ##STR23## wherein at least one of X, Y, and Z is --SO.sub.3 H or --SO.sub.3 --SALT;

• the remainder of X, Y and Z are independently --SO.sub.3 H, --SO.sub.3 --SALT, --OH, or H;
• where SALT is an alkali metal cation, ammonium, alkylammonium, polyalkylammonium, alkoxyammonium, or polyalkoxyammonium ion, the alkyl portions of each independently containing 1-6 carbon atoms;
• LINK is either --O-- or --O----(C.dbd.O)--O--;
• and BLOCK is described by the formula ##STR24## where R.sup.1 is hydrogen, carboxylate (--CO.sub.2 H), an alkyl group having 1-6 carbons, or ARYL;
• wherein ARYL is an unsubstituted phenyl, or phenyl substituted independently one or more times by --NO.sub.2, --OR.sup.3, where R.sup.3 is an alkyl having 1-6 carbons;
• or --(CH).sub.n --CO.sub.2 --M, where n=0-3 and M is Li.sup.+, Na.sup.+, K.sup.+, or NH.sub.4.sup.+ ;
• the remaining positions on the aromatic ring A are optionally independently substituted one or more times by --NO.sub.2, --OR.sup.3, or --(CH).sub.n --CO.sub.2 --M;
• or two adjacent positions on aromatic ring A, taken in combination, form a fused 6 membered ring to give a naphthyl structure;
• or substituents on two adjacent positions on aromatic ring A, taken in combination, form a methylenedioxy structure;
• or BLOCK is described by the formula ##STR25## where the remaining positions on aromatic rings B and C are optionally independently substituted one or more times by halogen, --NO.sub.2, --OR.sup.4, and --NR.sup.5 R.sup.6, where R.sup.4, R.sup.5 and R.sup.6 are independently alkyl groups having 1-6 carbons;
• or LINK is --O-- and BLOCK is described by the formula ##STR26## wherein R.sup.7 is H or Me;
• and R.sup.2 is H, --OH, --OR.sup.4, or --NR.sup.5 R.sup.6 ;
• wherein the concentration of said compound is greater than 10 nanogram per milliliter and less than 10 milligrams per milliliter.